I want to avoid any CEL eliminators. I have read that almost any after market header will cause a check engine light to come on, but I thought it’s just because most after market headers DONT have CAT’s.
Some direction would be awesome!
The check engine light comes on because the headers can cause the O2 sensor to send values outside of the expected range.
It could also be because the person who installed the headers failed to install an O2 sensor.
With most headers you must drill a hole in the collector and weld in a bung for the O2 sensor. You may also need an extension cable for the wiring harness.
If done correctly you should not have a check engine light.
You must also use a set of low restriction catalytic converters if you don’t want the check engine light. This is because on a modern engine there will be a second O2 sensor on the other side of the catalytic converter. This second O2 sensor monitors the performance of the catalytic converter. If there is no catalytic converter to monitor the computer will consider this a fault and turn on the check engine light.
Many of the aftermarket performance muffler companies also sell low restriction catalytic converters.